Adjustable plumb bob



May 30 1950 c. G. BYNUM ADJUSTABLE PLUMB BOB Filed Jan. l0, 1948 Patented May 30, 1950 UNITED STATES TENT OFFICE ADJUSTABLE PLUMB BOB Charles Gcynum, Boulder, Colo.

Application January 10, 1948, Serial No. 1,619

2 claims. 1

This invention relates to improvements in plumb bobs and has for its objects the provision of a device of this character equipped with a suspension string or cord and :provided with means whereby the cord may be lengthened or shortened to meet different working conditions.

One object of this invention is to produce a plumb bob of a simple and substantial construction that can be manufactured at a comparatively low cost and which can be conveniently operated.

A further object is to produce a plumb bob of the type indicated which shall have a minimum of parts, each of such design that they can be produced by automatic machines and which can be easily assembled. and disassembled.

Another object of the invention is to produce a plumb bob of such construction that the string remains in any desired adjusted position.

The above and other objects that may become apparent as this description proceeds are attained by means of a construction and an arrangement of parts that will now be described in detail and for this purpose reference will be had to the accompanying drawing in which the invention has been illustrated in its preferred form, and in which:

Figure 1 is a View partly in elevation and partly in diametrical section taken on line I-I, Figure 2;

Figure 2 is a top plan view looking through plane 2 2, in Figure 1;

Figure 3 is a section taken on line 3-3, Figure 1;

Figure 4 is a side elevation of the spool;

Figure 5 is a top plan view of the spool shown in Figure 4; and

Figure 6 is a bottom plan view thereof.

In the drawing reference numeral I Il designates the body of the plumb bob which may be of any suitable material, preferably brass. The plumb bob has the general shape of a truncated cone, the frustoconical surface extending from point II to point I2. The truncated end is replaced with a conical tip I3 that has a threaded connection with the plumb bob as indicated at Il. Above line I I, the body of the plumb bob is cylindrical and terminates at line I5. The base of the plumb bob body is provided with a central axial hole I3 that is cylindrical and has a smooth wall and this terminates` in a downwardly extending threaded hole I 1. A spool like that shown in Figures 4, 5 and 6 is provided, which has a central cylindrical portion I8 that terminates in end anges I9 and 20. In the drawing the inside 55 surfaces of the fianges have been shown as frustoconical, but the flanges may be formed with the inner and outer surfaces parallel, if desired. It will be noted that the upper flange I9 is of smaller diameter than the lower nange and the latter is provided with a cut-out or notch 2|, for a purpose which will hereinafter appear. The upper surface of flange I9 is preferably provided with a screwdriver slot 22. Extending downwardly from the under side of flange 20 is a cylindrical portion 23 that fits the cylindrical opening I6 in the manner shown in Figure 1. Cylindrical portion 23 terminates in a threaded part 24 that extends into a threaded opening Il. It will be observed that cylindrical portion 23 terminates in a shoulder 25 that abuts a cooperating shoulder at the bottom of opening I6 leaving a space be tween the lower flange of the spool and the upper surface of the plumb bob. Positioned 'between the plumb bob and the under surface of the lower ilange is a cup-like member 26 that has a center opening for the reception of cylindrical portion 23 that serves as a pivot about which the cup rotates. The wall of the cup is provided with a threaded surface 2I near its upper end for the reception of the inwardly threaded flange 28 of the removable closure 29. The closure has a central opening 30 through which the plumb line 3I extends. The inner surface of member 26 has an eyelet 32 through which the plumb line passes in the manner shown in Figure 1. The spool is provided with an opening 33 through which the end of the plumb line passes for the purpose of securing it to the spool.

It will be evident from the above that after the spool has been positioned in the plumb bob as shown in Figure 1 and tightened, it will remain Stationary. The cup-like member 26 can rotate about pivot 23, and if it is rotated in counterclockwise direction as indicated by the arrow in Figure 3, it will Wind the plumb line onto the center I8 of the spool. In Figure 3 the rotation of the cup-like member has been shown as counterclockwise, but it is immaterial in which Way the cup rotates. After the line has been wound onto the spool, however, it is evident that it must rotate in one direction to wind it and in the opposite direction to unwind it. Notch 2| is for the purpose of permitting the spool to be removed, providing, as it does, a passage for the eyelet 32.

When the plumb bob is not in use the line is wound onto the spool and since the line is provided at its end with a loop like that designated by reference numeral 34, it can be wound tightly onto the spool. When the plumb bob is to be used ascenso the required length of the line is unwound. Due to the friction of the parts the line will not unwind unless either an eXtra tension is applied to the parts, or housing 26 is rotated in the proper direction to unwind the line. The conical point I3 is preferably made from hardened steel so as to retain its shape as long as possible.

From the above it will be seen that the device, ignoring the point I3, consists of only four members: one being the plumb bob itself, another the spool, the third member, the rotatable cup-member 26, and the fourth the closure or cap 29. All,`

of the parts are of such design that they can be readily made by automatic machinery and quicklyV assembled.

This plumb bob is well adapted to be carried in a tool box because when` the plumb line, is

wound onto the spool, it does not become u nwound or tangled and the whole assembly occupies a` comparatively small space.

Having describedithe invention, what is claimed as new is:

1. A plumb bob comprising a substantially-con-- ica-l body having a substantially flat base providedv at its center with an axial opening that terminates in a threaded opening of smaller diameter, forming a shoulder, a spool having one end provided with an axial projection having a `cylindrical surface adjacent the spool, of a diameter to t the aXialopening in the plumb. bob, said projection terminating in a threaded p rojection of a smaller diameter than the cylindrical portion and of a Size to fit the threaded opening in the plumb bolov body, there being an annular Shoulder between the Cylindrical part and, the threaded part, the distance from the lower .end surface of the spool to the shoulder on the p1zo jeetion being greater than the distance from the base of the plumb bob body to the upwardly facing shoulder in the axial opening, whereby a space is formed between the lower end of the spool and the base surface when the spool is in position, a cup member having a bottom of a thickness less than the distance between the opposed surfaces of the plumb bob base and the spool, the bottom of the cup having a center opening, said cup member being positioned with its bottom in the space between the spool and the plumb bob body, the inner wall of the cup having an eyelet for guiding a plumb line, and a cap threadedly connected 'withthe upper end of the cup, said cap having a central opening for the plumb line.

2: A device in accordance with claim 1 in which theY lower flange of the spool has a diameter greater than that of the upper flange.

CHARLES G. BYNUM.

CITED- The4 following references are of record in the fileof this patent-zV Number Name Date 205,320 Turner June-25, 1878 748,132 Wolf' Dec. 29, 1903 916,608 Schmidtkel Mar. 30, 1909 151326,669` Gar-ner May 21, 1912 2,445,332 Nelson July 20, 1948 FOREIGN PATENTS NumberY Country Y Date` 181,572 Switzerland.'y A 1935 184,913 Switzerland 11935 

